Ladder and process of manufacturing the same



W. A. BILGER AND A. C. WALKER.

LADDER AND PROCESS OF MANUFACTURING THE SAME.

APPLICATION FILED MAY 29, 1921- Patented July 111, 1922.

WITNESSES:

I N VEN TORS: Wafiez: .1115 ilglrr 4&4

A TTOEYAS.

,vilan (3 Walker;

UNITED STATES PATENT OFFICE.

WALTER A. BILGER AND ALAN C. ASSIGNORS TO THE AMERICAN SYLVANIA, ACORPORATION OF LADDER AND PROCESS OF MANUFACTURING THE SAME.

To all whom it may concern.

Be it known that we, IVALTER A. BILGER and ALAN C. WALKER, citizens ofthe United States, residing in Philadelphia, in the county ofPhiladelphia andlState of Pennsylvania, United States of America, haveinvented certain new and useful Improvements in Ladders and Processes ofManufacturing the Same, whereof the following'is a specification,reference being had to the accompanying drawings.

he invention relates especially and to the tures.

The actual use to ladders, and more to ladders constructed of metal artof manufacturing such strucof metal ladders constructed according tocustomary practice heretofore (either of pipe fittings, or of standardrolled metal shapes) has been exceedingly limited, owing to theexcessive weight of such ladders, which rendered them too unwieldy forgeneral purposes. This objection we have entirely overcome byconstructing the constituent elements of the ladder (i. e., the siderails and the rungs) of comparatively thin sheet metal. According to ourinvention, suitable blanks of sheet metal may be shaped into tubularforms which will have the necessary stiffness and rigidity, and ladderelements and sections thus-made may be assembled and securedtogether,preferably by welding, so as to avoid the necessity for anyspecial or separate fastening means which would add materially to theweight of the completed ladder structure.

Other objects and attendant advantages of ourinvention will becomeapparent from the detailed description which follows:

In the drawings, Fig. I is an elevation of a sectional ladderconveniently embodying our invention, portions thereof being broken awayand shown in section for the sake of showing certain details ofconstruction more clearly.

Fig. II is a fragmentary detail view on a larger scale, showing aportion of the ladder at the region of juncture of a. rung with one ofthe side rails.

Fig. III is a detail section taken as indicated by the line III-III inFigs. I and II.

Fig. IV is a cross section along the plane of the arrows IV-IV in Fig.II.

Specification of Letters Patent.

Application filed May 20,

" 6. Either prior to or in the tion is completed Patented July 11, 1922.1921. Serial No. 471,185.

Fig. V is a view, similar to Fig. IV, of a slightly modified form of ourinvention.

he composite ladder structure shown in Fig. I is made up of counterpartsectional units comprehensively indicated by the numerals l, 2. Each ofthese sections 1 and 2 comprises tubular side rails 3, 3, and unitingrungs 5, 5 which interconnect said rails at suitable uniform intervals.Portions of the side rails 3, 3 at one end of each ladder section arereduced and shouldered as shown at 4, 4, and thus rendered capable ofbeing telescopically inserted within the ends of the side rails of anadjacent ladder section.

The tubular side rails 3, 3 of the ladder sections are preferablyconstructed from blank sheet metal strips bent, in any approved manner,to that cross sectional configuration. In the finished tubes, the edges,of the blanks meet along a longitudinal seam course of the bendingoperation, these edges are indented at intervals to provide laterallyprojecting offsets 7, 7 which when the bending operamatch up at oppositesides, of the longitudinal seam 6, as shown in Fig. III,'and togetherconstitute apertured bosses in which the rungs 5 are afterward received.In the present instance, the ofi'sets 7, 7 are made arcuate in order toconform to the circular crosssectional configuration of the cylindricalrungs shown; but it is evident that they may be any other desired shape,depending upon the form of the rungs which are to be received in thebosses.

Like the side rails 3, 3, the rungs 5, 5, are' preferably tubular andformed from sheet metal strip blanks so bent that their edges meet alonga longitudinal seam as indicated at 8 in the drawings. The ends of therungs are inserted in the apertured bosses of the side rails 3, 3 as faras permitted by their engagement with the inner wall of said rails assuggested in Fig. IV.

The ladder elements 3, 3 and 5, 5 may be secured to each other in anyapproved way. In order to avoid adding any appreciable weight to thecompleted ladder structure by the union, we prefer to weld the elementstogether. For this purpose, it is best to form the Welds Within thecrotches or angles between the rails and rungs, over regions indicatedin dotted lines at 9 in Figs. II and III. This results not only inuniting said elements. but also in permanently joining the edges ofadjacent port-ions of the seam (3 at each side of the rungs.

Referring now, to the modification of our invention in Fig. V, it willbe noted that the structure there represented is, in the main, preciselythesame as the first described form except that the side rail indicatedat 15 is oval in cross section instead of circular as before.

From the foregoing, it will be readily seen that ladders constructedaccording to our invention may be made so light as to compare favorablywith those ordinarily made of wood. thus rendering them just as capableof general use as the latter.

While we have herein shown and described an oval cross sectionalconfiguration for one of the ladder elements as suggestive of variation.it is obvious that various other shapes, either of the side rails or therungs, may be employed without departing from the spirit of ourinvention.

Having thus described our invention, we claim:

1. A metallic ladder comprising tubular side rails, each provided atintervals with pairs of spaced integrally formed lips, projectingoutward. and a series of tubular rungs respectively inserted into thetubularrails between opposed pairs of lips and welded thereto.

2. A metallic ladder comprising tubular side rails formed of blank sheetmetal strips with their edges meeting in a seam extending longitudinallyalong the inner side of the side rails, said edges being complementarilyindented at opposite sides of said seam to provide them with integrallaterally extending offsets by expansion of the metal outwardly formingspaced'lips to receive therebetween the ladder rungs, and tubular rungshaving their ends inserted into the tubular side rails and between corresponding bosses of said side rails and welded to said bosses.

3. The process of manufacturing metallic ladders which consists informing tubular side rails from blank strips of sheet metal having theiropposite longitudinal edges notched at intervals; inserting the ends ofthe ladder rungs in the receiving apertures formed along the seam of thetubular side rails by registering notchesfand welding the side rails andthe rungs together in the crotches between them.

4. The process of manufacturing metallicladders which consists informing tubular side rails from blank strips of sheet metal having theiropposite longitudinal edges complelnentarily offset, laterally andoutwardly at intervals to form pairs of spaced segmental lips,'insertingthe ends of the ladder rungs into the side rails and between opposedpairs of spaced lips to connect the side rails, and finally uniting thediverging edges of the lips by welding to form rung embracing bosses.

5. The process of manufacturingmetallic ladders which consists inindenting strips of metal at intervals along both edges to formsegmental lips. bending said strips transversely to form tubular siderails with the lips in opposition to form pairs, uniting said side railsby inserting theends of tubular rungs into the side rails and betweenopposed pairs of lips, and finally welding the rungs and the lips toform an integral structure.

6. The process of manufacturing metallic ladders which consists inindenting strips of sheet metal along both longitudinal edges at spacedintervals to form segmental lips, flexing said strips transversely toform tubular side rails and to bring the lips in opposition to formpairs, connecting a pair of such side rails by inserting the ends oftubular rungs into the hollows ofthe side rails 'and between opposedpairs of spaced lips,

and finally uniting the ends of the rungs to the lips by welding to formrung embracing bosses.

In testimony whereof, we have hereunto signed our names at Philadelphia,Pennsylvania, this 10th day of May, 1921.

IVALTER A. BILGER. ALAN C. l/VAIJKER- Witnesses:

HORACE THEBLE, EDNA M. MASSEY.

